Polymer compositions

ABSTRACT

An injection solution for injecting into a subterranean reservoir to enhance production and recovery of oil from the reservoir is disclosed. In one embodiment, the injection solution is prepared by mixing a sufficient amount of a pumpable, stable and substantially anhydrous polymer suspension in an aqueous fluid for the polymer to be hydrated in less than or equal to 4 hours, resulting in the injection solution containing a polymer concentration ranging from 100 ppm to 50,000 ppm. The injection solution has a filter ratio of less than or equal to 1.5 at 15 psi using a 1.2 μm filter. The polymer suspension comprises a powder polymer having an average molecular weight of 0.5 to 30 Million Daltons suspended in a water soluble solvent having an HLB of greater than or equal to 8 and selected from a group, at a weight ratio from 20:80 to 80:20.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims benefit under 35 USC 119 of U.S. ProvisionalPatent App. No. 62/073,184 with a filing date of Oct. 31, 2014, which isincorporated herein by reference in its entirety and for all purposes.This application claims benefit under 35 USC 119 of U.S. ProvisionalPatent App. No. 62/073,174 with a filing date of Oct. 31, 2014, which isincorporated herein by reference in its entirety and for all purposes.This application claims benefit under 35 USC 119 of U.S. ProvisionalPatent App. No. 62/073,179 with a filing date of Oct. 31, 2014, which isincorporated herein by reference in its entirety and for all purposes.This application claims benefit under 35 USC 119 of U.S. ProvisionalPatent App. No. 62/213,495 with a filing date of Sep. 2, 2015, which isincorporated herein by reference in its entirety and for all purposes.

TECHNICAL FIELD

The present disclosure generally relates to polymer compositions for usein enhanced oil recovery, and systems and methods for preparing andtransporting polymer compositions.

BACKGROUND

Reservoir systems, such as petroleum reservoirs, typically containfluids such as water and a mixture of hydrocarbons such as oil and gas.To remove (“produce”) the hydrocarbons from the reservoir, differentmechanisms can be utilized such as primary, secondary or tertiaryprocesses. In a primary recovery process, hydrocarbons are displacedfrom a reservoir through the high natural differential pressure betweenthe reservoir and the bottom-hole pressure within a wellbore. In orderto increase the production life of the reservoir, secondary or tertiaryrecovery processes can be used (“enhanced oil recovery” or EOR).Secondary recovery processes include water or gas well injection, whiletertiary methods are based on injecting additional chemical compoundsinto the well, such as surfactants and polymers, for additionalrecovery.

For EOR applications, polymers are added as an emulsion or as powderswhich are then mechanically mixed directly into water. In eitheremulsion or powder form, the preparation from start to finish takeshours to complete with multiple mixing/holding tanks and/or specialequipment. Additionally, the polymer powder cannot be convenientlypumped, and must be safely transported as bulk chemicals.

In the form of polymer emulsions, polymers are suspended as emulsion ina hydrocarbon carrier fluid such as diesel, mineral oil, etc. There areissues with lumping and dispersing the emulsions into water. Theemulsions must be mixed in holding tanks for a considerable length oftime for hydration to occur. Emulsions leave amounts of carrier oil inthe injected solution, which may have an impact on EOR efficiency,particularly in low permeability reservoir. U.S. Pat. No. 8,383,560discloses a method for dissolving an emulsion to a final polymerconcentration of 500 to 3000 ppm for EOR applications in a complexprocess requiring multi-step mixing under different conditions.

With the use of powders, particularly when the product is used foroff-shore platforms (e.g., on a floating production, storage andoffloading or FPSO), elaborate powder equipment is required for thehandling of very large quantities of powder. Additionally, much time isneeded to suspend the polymer powders directly into water, as well asnecessary special equipment for the mixing of powders into water.USP2004/008571 discloses an apparatus and method for hydratingparticulate polymer, including a pre-wetter, a high-energy mixer, and ablender. USP 2004/0136262 discloses an apparatus and method for wettingpowdered material for subsequent distribution of the material in bulkwater for EOR applications. USP 2012/0199356 discloses an installationwhich includes a “polymer slicing unit” for the dissolution of polymerpowder for EOR applications.

There is a need for improved polymer compositions/preparations, andmethods to prepare/transfer such polymer compositions/preparations forconvenient and efficient EOR applications, particularly off-shore EOR.

SUMMARY

In one aspect, the invention relates to an injection solution forinjecting into a subterranean reservoir to enhance production andrecovery of oil from the reservoir. In one embodiment, the injectionsolution can be prepared by mixing a sufficient amount of a pumpable,stable and substantially anhydrous polymer suspension in an aqueousfluid for the polymer to be hydrated in less than or equal to 4 hours,resulting in the injection solution containing a polymer concentrationranging from 100 ppm to 50,000 ppm. The injection solution has a filterratio of less than or equal to 1.5 at 15 psi using a 1.2 μm filter. Thepolymer suspension comprises a powder polymer having an averagemolecular weight of 0.5 to 30 Million Daltons suspended in a watersoluble solvent having an HLB of greater than or equal to 8 and selectedfrom the group of surfactants, glycol ethers, alcohols, co-solvents, andmixtures thereof, at a weight ratio of powder polymer to water solublesolvent ranging from 20:80 to 80:20. The aqueous fluid is selected fromany of surface water, water recovered from a production well, sea water,synthetic water, produced reservoir brine, reservoir brine, fresh water,produced water, water, saltwater, brine, synthetic brine, syntheticseawater brine, and mixtures thereof.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example that compares the viscosities of a polymer solutionprepared from the polymer suspension with a prior art polymer solutionprepared directly from a powder polymer.

FIG. 2 is an example that compares the rheology of a polymer solutionprepared from the polymer suspension with a prior art polymer solutionprepared directly from a powder polymer, and a prior art polymersolution prepared from a polymer emulsion.

FIG. 3 is an example that compares the filterability of a polymersolution prepared from the polymer suspension with a polymer solutionprepared from a polymer emulsion of the prior art.

DETAILED DESCRIPTION

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

“A” or “an” means “at least one” or “one or more” unless otherwiseindicated. As used herein “multi-” or “plurality” refers to 2 or more.

“Comprise”, “have”, “include” and “contain” (and their variants) areopen-ended linking verbs and allow the addition of other elements whenused in a claim. “Consisting of” is closed, and excludes all additionalelements.

“Consisting essentially of” excludes additional material elements, butallows the inclusions of non-material elements that do not substantiallychange the nature of the invention.

“Effective amount,” refers to an amount sufficient to effect ameasurable difference over not including the amount. For example, aneffective amount of polymer in a polymer slug would increase oilrecovery over only using the equivalent slug without polymer.

“Equal” refers to equal values or values within the standard of error ofmeasuring such values. “Substantially equal” refers to an amount that iswithin 3% of the value recited.

The terms “operation” and “application” may be used interchangeabilityherein, as in EOR operations or EOR applications.

“Filterability” refers to the mobility control property of an aqueousflooding fluid containing polymer, or the ability to move unimpededthrough the formation without blocking the pores of the formation.“Filter ratio” (or filterability ratio) test is a recognized laboratorytest to measure the ability of an aqueous flooding fluid to move througha subterranean formation without blocking the pores of the formation, asdescribed in The American Petroleum Institute standards RP 63. Ideally,an aqueous flooding fluid should pass through the filter at a constantrate throughout the test, causing no pore-blocking during filtration,with a filter ratio=1.0. The actual measured filter ratio istypically >1.0, however, so an upper limit to the filter ratio under aspecific set of conditions is normally used in order to determine thesuitability of an aqueous flooding fluid for use in a mobility controlapplication.

For certain applications, including many enhanced oil recovery (EOR)applications, it can be desirable that a polymer composition flowsthrough a hydrocarbon-bearing formation without plugging the formation.Plugging the formation can slow or inhibit oil production. This is anespecially large concern in the case of hydrocarbon-bearing formationsthat have a relatively low permeability prior to tertiary oil recovery.

One test commonly used to determine performance in such conditionsinvolves measuring the time taken for given volumes/concentrations ofsolution to flow through a filter, commonly called a filtration quotientor Filter Ratio (“FR”). For example, U.S. Pat. No. 8,383,560, which isincorporated herein by reference, describes a filter ratio test methodwhich measures the time taken by given volumes of a solution containing1000 ppm of active polymer to flow through a filter. The solution iscontained in a cell pressurized to 2 bars and the filter has a diameterof 47 mm and a pore size of 5 microns. The times required to obtain 100ml (t100 ml), 200 ml (t200 ml), and 300 ml (t300 ml) of filtrate weremeasured. These values were used to calculate the FR, expressed by theformula below:

${F\; R} = \frac{{{\,^{t}300}\mspace{14mu}{ml}} - {{\,^{t}200}\mspace{14mu}{ml}}}{{{\,^{t}200}\mspace{14mu}{ml}} - {{\,^{t}100}\mspace{14mu}{ml}}}$

The FR generally represents the capacity of the polymer solution to plugthe filter for two equivalent consecutive volumes. Generally, a lower FRindicates better performance. U.S. Pat. No. 8,383,560 explains that adesirable FR using this method is less than 1.5.

However, polymer compositions that provide desirable results using thistest method have not necessarily provided acceptable performance in thefield. In particular, many polymers that have an FR (using a 5 micronfilter) lower than 1.5 exhibit poor injectivity—i.e., when injected intoa formation, they tend to plug the formation, slowing or inhibiting oilproduction.

A modified filter ratio test method using a smaller pore size (i.e., thesame filter ratio test method except that the filter above is replacedwith a filter having a diameter of 47 mm, a pore size of 1.2 microns,and a lower pressure of 15 psi provides a better screening method.Injection solutions and polymer compositions hydrated in aqueous fluidsfor injection solutions consistent with the disclosure herein canprovide a FR of less than or equal to 1.5 (i.e., filter ratio of 1.5 orless) at 15 psi using the 1.2 micron filter. In field testing, theseinjection solutions and polymer compositions hydrated in aqueous fluidsfor injection solutions consistent with the disclosure herein canexhibit improved injectivity over prior art polymercompositions—including other polymer compositions having an FR (using a5 micron filter) of less than 1.5. As such, the injection solutions andpolymer compositions hydrated in aqueous fluids for injection solutionsconsistent with the disclosure herein are suitable for use in a varietyof oil and gas applications, including EOR.

Filter ratio (FR) can also be determined using the standard proceduredescribed, for example, in Koh, H. Experimental Investigation of theEffect of Polymers on Residual Oil Saturation. Ph.D. Dissertation,University of Texas at Austin, 2015; Levitt, D. The Optimal Use ofEnhanced Oil Recovery Polymers Under Hostile Conditions. Ph.D.Dissertation, University of Texas at Austin, 2009; and Magbagbeola, O.A. Quantification of the Viscoelastic Behavior of High Molecular WeightPolymers used for Chemical Enhanced Oil Recovery. M.S. Thesis,University of Texas at Austin, 2008, each of which is herebyincorporated by reference in its entirety.

For purposes of this disclosure, including the claims, the filter ratio(FR) can be determined using a 1.2 micron filter at 15 psi (plus orminus 10% of 15 psi) at ambient temperature (e.g., 25° C.). The 1.2micron filter can have a diameter of 47 mm or 90 mm, and the filterratio can be calculated as the ratio of the time for 180 to 200 ml ofthe injection solution to filter divided by the time for 60 to 80 ml ofthe injection solution to filter.

${F\; R} = \frac{{{\,^{t}200}\mspace{14mu}{ml}} - {{\,^{t}180}\mspace{14mu}{ml}}}{{{\,^{t}80}\mspace{14mu}{ml}} - {{\,^{t}60}\mspace{14mu}{ml}}}$For purposes of this disclosure, including the claims, the injectionsolution is required to exhibit a FR of 1.5 or less.

“HLB” or “hydrophilic-lipophilic balance” refers to the nature of asolvent to have a balance between aqueous and nonaqueous phases, usefulfor visualizing the ease of mixing the solvent into water. The HLB scalewas derived initially for surfactants and provides a means of comparingthe relative hydrophilicity of amphiphilic molecules. As used herein,HLB scale refers to surfactants as well as solvents withpseudo-surfactant qualities, such as glycol ethers. A composition withlow HLB (<8) has a high affinity for oily or nonaqueous phases and isgenerally highly insoluble in water. A composition with a high HLB (>8)may generally have a high affinity for water and may form clear mixtureswith water, even at high concentrations. Complete water solubilitytypically occurs at an HLB of about 7.3. Solvents with HLB values abovethis mark are typically miscible with water, while those below thisvalue are only partially soluble in water.

“Polymer suspension” may be used interchangeably with “slurry,” or“polymer slurry,” referring to a multi-phase composition of polymersolids (particles) in a liquid phase, with the liquid phase being thecontinuous phase. The liquid phase is a water soluble solvent. A polymersuspension is not the same as a polymer emulsion, as the emulsion of apolymer emulsion is the result of a chemical process by emulsifyingusing surfactant and optionally co-surfactants and mechanicalhomogenization in the presence of oil phase, causing emulsification.

“Pumpable” refers to a state in which the viscosity of the polymersuspension allows the polymer suspension to be pumped through a pump,tubing, equipment to produce hydrocarbons, etc. In one embodiment, thepolymer suspension may be pumpable when the viscosity is less than orequal to 15,000 cp measured at 24° C. and 10 inverse seconds.

“Turbidity” refers to the suspension of fine colloidal particles that donot settle out of solution and can result in a “cloudiness.” Turbidityis determined by a Nepholometer that measures the relative amount oflight able to pass through a solution. Turbidity is reported as NTU(Nepholometric Turbidity Units).

“Pore volume” or “PV” fraction as used herein refers to the total volumeof pore space in the oil reservoir that is contemplated in a reservoirsweep (e.g., contacted pore space at alkali-surfactant-polymer (ASP),surfactant-polymer (SP), alkali-polymer (AP), and/or polymer drive (PD)mobility ratio).

“Pore throat” refers to openings in sand/rock formation. Pore throatsize in formation forms a continuum from the sub-millimeter to thenanometer scale. For measures of central tendency (mean, mode, median),pore throat sizes (diameters) are generally greater than 2 μm inconventional reservoir rocks, from about 2 to 0.03 μm in tight-gassandstones, and from 0.1 to 0.005 μm in shales.

“Slug” refers to an amount of a composition that is to be injected intoa subterranean reservoir.

“Substantially anhydrous” as used herein refers to a polymer suspensionwhich contains only a trace amount of water. Trace amount means nodetectable amount of water in one embodiment; less than or equal to 3wt. % water in another embodiment; and containing less than or equal toany of 2.5%, 2%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%,0.1%, 0.05% or 0.01% water in various embodiments. A reference to“polymer suspension” refers to a substantially anhydrous polymersuspension.

Disclosed is a preparation of a substantially anhydrous polymersuspension comprising or consisting essentially of powder polymer and awater soluble solvent, which can be conveniently prepared, contained,and transported to well sites for oil and gas operations (e.g., EORapplications or operations). The polymer suspension is stable and can bekept in a holding tank for a considerable period of time. The polymersuspension is water soluble. It can also be transported to a site viapipeline, which is not attainable with the prior art preparations ofpowder polymer/polymer emulsion. At the EOR site, the polymer suspensioncan be mixed and diluted with water to the desirable polymerconcentration for injection. The polymer suspension obviates the needfor special equipment currently required for the handling and mixing ofpowder polymer and polymer emulsions.

The substantially anhydrous polymer suspension comprises 20-80 wt. % ofa powder polymer in a matrix of 80-20 wt. % a water soluble solvent, andoptionally other additives. In another embodiment, the substantiallyanhydrous polymer suspension consists essentially of 30-70 wt. % of apowder polymer in matrix of 70-30 wt. % water soluble solvent, andoptional other additives. In another embodiment, the weight ratio ofpowder polymer to water soluble solvent ranges from 20:80 to 80:20. Inyet another embodiment, the weight ratio of powder polymer to watersoluble solvent ranges from 30:70 to 70:30. In yet another embodiment,the weight ratio of powder polymer to water soluble solvent ranges from40:60 to 60:40.

Polymer for Use in Suspension:

The powder polymer for use in the suspension is selected or tailoredaccording to the characteristics of the reservoir for EOR treatment suchas permeability, temperature and salinity. Examples of suitable powderpolymers include biopolymers such as polysaccharides. For example,polysaccharides can be xanthan gum, scleroglucan, guar gum, any mixturesthereof (e.g., any modifications thereof such as a modified chain), etc.Indeed, the terminology “mixtures thereof” or “combinations thereof” caninclude “modifications thereof” herein.

Examples of suitable powder synthetic polymers include polyacrylamides.Examples of suitable powder polymers include synthetic polymers such aspartially hydrolyzed polyacrylamides (HPAMs or PHPAs) andhydrophobically-modified associative polymers (APs). Also included areco-polymers of polyacrylamide (PAM) and one or both of 2-acrylamido2-methylpropane sulfonic acid (and/or sodium salt) commonly referred toas AMPS (also more generally known as acrylamido tertiobutyl sulfonicacid or ATBS), N-vinyl pyrrolidone (NVP), and the NVP-based syntheticmay be single-, co-, or ter-polymers. In one embodiment, the powdersynthetic polymer is polyacrylic acid (PAA). In one embodiment, thepowder synthetic polymer is polyvinyl alcohol (PVA). Copolymers may bemade of any combination or mixture above, for example, a combination ofNVP and ATBS.

Examples of suitable powder polymers include biopolymers or syntheticpolymers. Examples of suitable powder polymers can also include anymixture of these powder polymers (including any modifications of thesepowder polymers).

In one embodiment, the powder polymer is an anionic polyacrylamidehaving a charge ranging from 0 to about 40%, which may be resultantbecause the reaction to form polyacrylamide generally starts with about0% to about 40% acrylic acid or acid salt. The polymer that may beformed with acrylic acid or an acid salt monomer is called anionicpolyacrylamide because the polymer itself contains a negative charge,which is balanced by a cation, usually sodium. A polymer made withlittle or no acid or acid salt is considered nonionic polyacrylamidebecause the polymer essentially contains no charge.

The powder polymer has an average molecular weights (Mw) of: 0.5 to 30Million Daltons in one embodiment; from 1 to 15 Million Daltons in asecond embodiment; at least 2 Million Daltons in a third embodiment;from 4 to 25 Million Daltons in a fourth embodiment; less than or equalto 25 Million Daltons in a fifth embodiment; and at least 0.5 MillionDaltons in a sixth embodiment.

The polymer powders have an average particle size of at least 5 mesh inone embodiment, 10-100 mesh in a second embodiment, and 40-400 mesh in athird embodiment. The polymer powder undergoes an additional milling,grinding, or crushing prior to mixing with the water soluble solvent inthe preparation, for a particle size of 1-1000 μm in one embodiment;from 10-500 μm in a second embodiment; at least 5 μm in a thirdembodiment; and from 20-500 μm in a fourth embodiment.

Water Soluble Solvent.

The water soluble solvent for use in the polymer suspension is selectedfrom one or more of surfactants (e.g., non-ionic surfactants), ethers(e.g., glycol ethers), alcohols, co-solvents, and combinations thereof,for an HLB of greater than or equal to 8 (e.g., at least 8) as measuredby methods known in the art, e.g., NMR, gas-liquid chromatography, orinvert emulsion experiments using Griffin's method or Davies's method.In one embodiment, the HLB is about 10.0 to about 20. In anotherembodiment, the HLB is less than or equal to 15. Examples of suitablewater soluble solvents can also include any mixture of these watersoluble solvents (including any modifications of these water solublesolvents). For example, the water soluble solvent can include a mixtureof non-ionic and anionic surfactants. The anionic surfactant can bepresent in an amount of less than or equal to 5 wt. % as a stabilizer.

In one embodiment, the viscosity of the water soluble solvent is any of10-1000 cP, such as between about 10-100, 100-200, 200-300, 300-400,400-500, 500-600, 600-700, 700-800, 900-1000, 10-300, 300-600, or600-1000 cP as measured by using any of a capillary or oscillatoryviscometer, or similar equipment. In one embodiment, the water solublesolvent has a cloud point of less than 90° C., such as between 25 and80° C., as measured by visual observation of wax forming according toany of ASTM D2500 or a constant cooling rate method (ASTM D5773).

Examples of suitable water soluble solvents include but are not limitedto alcohol ethoxylates (-EO-); alcohol alkoxylates (-PO-EO-); alkylpolyglycol ethers; alkyl phenoxy ethoxylates; an ethylene glycol butylether (EGBE); a diethylene glycol butyl ether (DGBE); a triethyleneglycol butyl ether (TGBE); polyoxyethylene nonylphenylether, branched;and mixtures thereof. In one embodiment, the water soluble solvent is analcohol selected from the group of isopropyl alcohol (IPA), isobutylalcohol (IBA) and secondary butyl alcohol (SBA). In another embodiment,the water soluble solvent is a low MW ether such as ethylene glycolmonobutyl ether.

In embodiments with the use of HPAM type synthetic polymers, a non-ionicsurfactant is used as the water soluble solvent. In yet anotherembodiment, a mixture of surfactants is used, e.g., non-ionicsurfactants and anionic surfactants in a weight ratio ranging from 6:1to 2:1. Examples of non-ionic surfactants for use as the water solublesolvents include ethoxylated surfactants, nonylphenol ethoxylates oralcohol ethoxylate, other ethoxylated surfactants and mixtures thereof.In another embodiment, the anionic surfactants are selected from thegroup of internal olefin sulfonates, isomerized olefin sulfonates, alkylaryl sulfonates, medium alcohol (C10 to C17) alkoxy sulfates, alcoholether [alkoxy]carboxylates, alcohol ether [alkoxy]sulfates, alkylsulfonate, α-olefin sulfonates (AOS), dihexyl sulfosuccinate andmixtures thereof. In yet another embodiment, the water soluble solventis selected from alkylpolyalkoxy sulfates as disclosed in U.S. Pat. No.8,853,136, or sulfonated amphoteric surfactants as disclosed in U.S.Pat. No. 8,714,247, or surfactants based on anionic alkyl alkoxylates asdisclosed in US Patent Publication No. 20140116689, all incorporatedherein by reference.

In one embodiment, the water soluble solvent is selected from isopropylalcohol (IPA), n-propyl alcohol, isobutyl alcohol (IBA), methyl-isobutylalcohol, secondary butyl alcohol (SBA), ethylene glycol monobutyl ether,diethylene glycol monobutyl ether, triethylene glycol monobutyl ether,and mixtures thereof. In one embodiment, the water soluble solvent is anionic surfactant selected from ethoxylated surfactants, nonylphenolethoxylates, alcohol ethoxylates, internal olefin sulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, alkyl sulfonate, α-olefin sulfonates (AOS), dihexylsulfosuccinates, alkylpolyalkoxy sulfates, sulfonated amphotericsurfactants, and mixtures thereof. Examples of suitable water solublesolvents can also include any mixture of these water soluble solvents(including any modifications of these water soluble solvents).

In one embodiment, the water soluble solvent is a co-solvent, and theco-solvent is selected from the group of an ionic surfactant, non-ionicsurfactant, anionic surfactant, cationic surfactant, nonionicsurfactant, amphoteric surfactant, ketones, esters, ethers, glycolethers, glycol ether esters, lactams, cyclic ureas, alcohols, aromatichydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons,nitroalkanes, unsaturated hydrocarbons, halocarbons, surfactantscommonly used for enhanced oil recovery applications, alkyl arylsulfonates (AAS), a-olefin sulfonates (AOS), internal olefin sulfonates(IOS), alcohol ether sulfates derived from propoxylated Ci₂-C₂oalcohols, ethoxylated alcohols, mixtures of an alcohol and anethoxylated alcohol, mixtures of anionic and cationic surfactants,disulfonated surfactants, aromatic ether polysulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, primary amines, secondary amines, tertiary amines,quaternary ammonium cations, cationic surfactants that are linked to aterminal sulfonate or carboxylate group, alkyl aryl alkoxy alcohols,alkyl alkoxy alcohols, alkyl alkoxylated esters, alkyl polyglycosides,alkoxy ethoxyethanol compounds, isobutoxy ethoxyethanol (“iBDGE”),n-pentoxy ethoxyethanol (“n-PDGE”), 2-methylbutoxy ethoxyethanol(“2-MBDGE”), methylbutoxy ethoxyethanol (“3-MBDGE”), (3,3-dimethylbutoxyethoxyethanol (“3,3-DMBDGE”), cyclohexylmethyleneoxy ethoxyethanol(hereafter “CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol (“MIBCDGE”),n-hexoxy ethoxyethanol (hereafter “n-HDGE”), 4-methylpentoxyethoxyethanol (“4-MPDGE”), butoxy ethanol, propoxy ethanol, hexoxyethanol, isoproproxy 2-propanol, butoxy 2-propanol, propoxy 2-propanol,tertiary butoxy 2-propanol, ethoxy ethanol, butoxy ethoxy ethanol,propoxy ethoxy ethanol, hexoxy ethoxy ethanol, methoxy ethanol, methoxy2-propanol and ethoxy ethanol, n-methyl-2-pyrrolidone, dimethyl ethyleneurea, and mixtures thereof. Examples of suitable co-solvents can alsoinclude any mixture of these co-solvents (including any modifications ofthese co-solvents)

When the polymer suspension is mixed with produced water in EORapplications, the water soluble solvent (e.g., a surfactant or a mixturethereof) dissolves and can produce a suspension of oil-in-water emulsionif the produced water included oil in the produced water.

Optional Additives:

The polymer suspension can optionally comprise one or more additives.Examples of optional additives include anionic surfactants, biocides,co-solvents, chelators, reducing agents/oxygen scavengers, stabilizers,etc., in an amount of less than or equal to 10 wt. % (of the totalweight of the polymer suspension). In one embodiment, a stabilizer isadded to further stabilize the suspended polymer. For example, ananionic surfactant can be present in an amount of less than or equal to5 wt. % as a stabilizer.

Preparation of Polymer Suspension:

Forming the polymer suspension can be done in any suitable manner. Thepolymer and water soluble solvent can be mixed together to form thepolymer suspension, e.g., in a conventional dry powder mixing/blendingsystem. For example, powder polymer is fed to a water soluble solvent ina tank with a feeder/hopper, then mixed together. The mixing is from 20minutes to 4 hours in one embodiment. In another embodiment, the polymersuspension is mixed and prepared in less than or equal to 30 minutes. Inyet another embodiment, the mixing is for at least 15 minutes and lessthan or equal to 1 hour. In a third embodiment, the mixing is for 24hours or less.

Properties of the Polymer Suspension:

Unlike the polymer emulsion of the prior art which separates if allowedto stand over a prolonged period of time, the polymer suspension isstable. A “stable suspension” or “stable polymer suspension” as usedherein refers to a polymer suspension which does not undergo substantialsettling after the polymer has been suspended in the water solublesolvent for a period of at least 2 hours. Furthermore, even settlementhappens, the polymer particles can still suspend again by simplyagitating the solution to re-generate the polymer suspension. In oneembodiment of a stable polymer suspension, the viscosity of the top,middle and bottom of the polymer suspension in a container (e.g., amixer or holding tank) varies less 15%. The stability of the polymersuspension can be evaluated by visual observation over time, orqualitatively by methods known in the art including light scattering andturbidity methods, for changes in turbidity of more than 25% over aperiod of at least 2 hours. In one embodiment, after the powder polymeris suspended in the water soluble solvent for a period of at least 2hours, there can be a turbidity decrease of at least 25%. In oneembodiment, after the powder polymer is suspended in the water solublesolvent for a period of at least 2 hours, there can be a turbiditydecrease of at least 50%. In one embodiment, after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hours,there can be a turbidity decrease of at least 75%. Moreover, in oneembodiment, a stable and substantially anhydrous polymer suspension canbe achieved by mixing the powder polymer into the water soluble solventfor less than or equal to 24 hours.

The polymer suspension can be clear, translucent, or slightly hazydepending on the solvent used. However, when the polymer suspension ismixed into an aqueous stream for a injection solution with a sufficientpolymer concentration for injection (e.g., less than or equal to 50,000ppm), the end result is a clear or almost clear injection solution withNTU of less than or equal to 20 in one embodiment; NTU of less than orequal to 15 in a second embodiment; NTU of less than or equal to 10 in athird embodiment; and NTU of less than or equal to 5 in a fourthembodiment. It should be noted that injection solutions prepared frompolymer emulsion are milky white, and injection solutions prepared frompowder polymer are hazy.

The polymer suspension is pumpable (e.g., with a pump such as avolumetric pump), allowing the polymer suspension to be transported viapipelines long-distance or under sea to off-shore locations. The polymersuspension remains stable and pumpable state even after 24 or 48 hoursafter forming, and can be hydrated in aqueous fluids for use ininjection streams.

Applications of the Polymer Suspension:

The polymer suspension can be stored, pumped, and transported (e.g., viaa pipeline, tanker, etc.) to a location for use in EOR applications. Thepolymer suspension can also be utilized in various mining, hydrocarbonrecovery and processing applications, such as in drilling operations(e.g., drilling fluids/dispersants, etc.), and reservoir injection asdrilling, fracturing fluids, recovery fluids, water shut-off andconformance control.

As the polymer suspension is concentrated, it can be hydrated in waterto a target polymer concentration in an aqueous medium for an injectionsolution with minimal if any lumps or clumps, without the intenseshearing/mixing for extended periods of time (>24 hours) as with thepolymer emulsions of the prior art, or with special equipment as withthe direct use of powder polymer. The polymer suspension can be hydratedfor immediate use in less than or equal to 4 hrs. in one embodiment; inless than or equal to 2 hours in a second embodiment; in less than orequal to 1 hr. in a third embodiment; and less than 30 minutes in afourth embodiment. The addition to an aqueous medium can be in the formof pouring, as into a container or tank, or by injection, as into apipeline using a pump and check valve, or by any other means known inthe art for dispersing a composition such as the polymer suspension intoan aqueous liquid. Depending on the embodiment, the aqueous medium andthe polymer suspension can be mixed in an in-line static mixer, dynamicmixer, downhole mixer, or in a mixing tank.

CEOR Applications:

For chemical enhanced oil recovery (CEOR) applications, the polymersuspension is dispersed into an aqueous stream in a sufficient amountfor an injection stream with a target hydrated polymer concentration andparticle size. The target concentration varies according to the type ofpolymer employed, as well as the characteristics of the reservoir, e.g.,petrophysical rock properties, reservoir fluid properties, reservoirconditions such as temperature, permeability, water compositions,mineralogy and/or reservoir location, etc. The polymer suspension issuitable for use in reservoirs with a permeability about 10 millidarcyto 40 Darcy.

The effective (or target) concentration of the hydrated polymer in theinjection stream ranges from 100 to 5000 ppm in one embodiment; lessthan or equal to 50,000 ppm in a second embodiment; less than or equalto 20,000 ppm in a third embodiment; and less than or equal to 10,000ppm in a fourth embodiment. The effective concentration of the polymerin the slugs allows a favorable mobility ratio under the reservoirconditions of temperature. Different slugs may comprise different typesas well as different amounts of polymer (and polymer suspensions). Inembodiments of the disclosure, the polymer suspension is mixed with theinjection fluid at ratios which result in the desired effective amountof polymer in the final mixed injection fluid. For example, 1 g of 30%active polymer suspension is added to 99 g of injection water to make3000 ppm polymer in the final mixed injection fluid. The ratios ofpolymer suspension to injection fluid is about 1:1000, such as 1:100,1:200, 1:500, 1:700, and so on. The polymer suspension can be able to bediluted to the target concentration in the injection stream directly orthrough the multiple dilution steps. For example, 30% active polymersuspension is hydrated to 1% polymer in the injection fluid, thendiluted again to make 3000 ppm polymer in the final mixed injectionfluid.

The polymer suspension may be passively or actively mixed with the waterfor a period ranging from 15 minutes to 4 hours in one embodiment, lessthan or equal to 2 hours in a second embodiment, and from 20 to 60minutes in a third embodiment. In one embodiment, the polymer suspensionis added into a stream of water, for example treated produced water,which then is mixed into the water passively through fluid motion. Inanother embodiment, the polymer suspension is mixed into the waterthough a mixer, such as an in-line static mixer or the like. In oneembodiment, the polymer suspension and water are mixed in a holding tankthrough the use of an active mixer, such as a static mixer, in-linemixer, dynamic mixer, downhole mixer, vacuum mixer, high shear mixer,dry powder-liquid blenders, and so on.

The hydrated polymer molecules in the injection stream have a particlesize (radius of gyration) ranging from 0.01 to 10 μm in one embodiment.One reservoir characteristic is the median pore throats, whichcorrespond to the permeability of the reservoirs. Depending on thereservoir, the median pore throats in reservoirs may range from 0.01 μmto several hundred micrometers. Since the size of hydrated polymers inwater range from 0.01 micrometer to several micrometers depending on thespecies, molecules, and reservoir conditions, in one embodiment,appropriate polymers are selected for the polymer suspension for theparticle size of the hydrated polymer to be less than or equal to 10% ofthe median pore throat parameters, allowing the hydrated polymerparticles to flow through the porous medium in an uninhibited manner. Inanother embodiment, the hydrated polymer particles have an averageparticle size ranging from 2 to 8% of the median pore throat size.

Polymer suspension can be hydrated by mixing into a water basedinjection fluid which can comprise water and optional additives such aschelators, co-solvents, reducing agents/oxygen scavengers, corrosioninhibitors, scale inhibitors, and/or biocides. The water based injectionfluid may then be injected into an injection well to recover additionaloil.

The water based injection fluid (e.g., injection solution) ischaracterized as having a filter ratio of less than or equal to 1.5 at15 psi using a 1.2 μm filter in one embodiment; less than or equal to1.2 at 15 psi using a 1.2 μm filter in a second embodiment; less than orequal to 1.10 at 15 psi using a 1.2 μm filter in a third embodiment; andless than or equal to 1.05 at 15 psi using a 1.2 μm filter in a fourthembodiment. In some embodiments, the injection solution can have afilter ratio of 1.5 or less (e.g., 1.45 or less, 1.4 or less, 1.35 orless, 1.3 or less, 1.25 or less, 1.2 or less, 1.15 or less, 1.1 or less,or less than 1.05) at 15 psi using a 1.2 μm filter. In some embodiments,the injection solution can have a filter ratio of greater than 1 (e.g.,at least 1.05, at least 1.1, at least 1.15, at least 1.2, at least 1.25,at least 1.3, at least 1.35, at least 1.4, or at least 1.45) at 15 psiusing a 1.2 μm filter. In some embodiments, the injection solutioncontains a polymer concentration ranging from 100 ppm to 50,000 ppm andhas a filter ratio of less than 1.5 at 15 psi using a 1.2 μm filter(e.g., in less than or equal to 4 hours).

In one embodiment, mixing (e.g., via a mixing tank or an in-line mixer)a sufficient amount of the polymer suspension in the aqueous fluid forthe polymer to be hydrated results in the injection solution in lessthan or equal to 4 hours. In one embodiment, mixing a sufficient amountof the polymer suspension in the aqueous fluid for the polymer to behydrated results in the injection solution in less than or equal to 2hours. In one embodiment, mixing a sufficient amount of the polymersuspension in the aqueous fluid for the polymer to be hydrated resultsin the injection solution in less than or equal to 1 hours. In oneembodiment, the injection solution is prepared by mixing the pumpable,stable and substantially anhydrous polymer suspension in an aqueousfluid in less than or equal to 4 hours. In one embodiment, the injectionsolution is prepared by mixing the pumpable, stable and substantiallyanhydrous polymer suspension in an aqueous fluid in less than or equalto 2 hours. In one embodiment, the injection solution is prepared bymixing the pumpable, stable and substantially anhydrous polymersuspension in an aqueous fluid in less than or equal to 1 hour. In oneembodiment the injection solution has a NTU of less than or equal to 20;a NTU of less than or equal to 15 in a second embodiment; and a NTU ofless than or equal to 10 in a third embodiment.

In one embodiment, a method of enhancing oil recovery in a subterraneanreservoir includes providing a wellbore in fluid communication with thesubterranean reservoir. The method also includes providing a polymersuspension, for example, such that the polymer suspension comprises apowder polymer having an average molecular weight of 0.5 to 30 MillionDaltons suspended in a water soluble solvent having an HLB of greaterthan or equal to 8 and selected from the group of surfactants, glycolethers, alcohols, co-solvents, and mixtures thereof, at a weight ratioof powder polymer to water soluble solvent ranging from 20:80 to 80:20.For example, the polymer suspension is substantially anhydrous. Themethod further includes providing an aqueous fluid, for example,selected from any of surface water, water recovered from a productionwell, sea water, synthetic water, produced reservoir brine, reservoirbrine, fresh water, produced water, water, saltwater, and mixturesthereof. The method further includes mixing a sufficient amount of thepolymer suspension in the aqueous fluid for the polymer to be hydratedresulting the injection solution, for example, in less than or equal to4 hours. The injection solution can contain a polymer concentrationranging from 100 ppm to 50,000 ppm and have a filter ratio of less thanor equal to 1.5 at 15 psi using a 1.2 μm filter. The method furtherincludes injecting the injection solution into the wellbore into thesubterranean reservoir.

In some embodiments, the wellbore is an injection wellbore associatedwith an injection well, and the method further includes providing aproduction well spaced apart from the injection well a predetermineddistance and having a production wellbore in fluid communication withthe subterranean reservoir such that the injection of the injectionsolution increases flow of hydrocarbons to the production wellbore. Insome embodiments, the wellbore is a hydraulic fracturing wellboreassociated with a hydraulic fracturing well, for example that may have asubstantially vertical portion only or a substantially vertical portionand a substantially horizontal portion below the substantially verticalportion. In some embodiments, the injection solution can function as adrag reducer, a hydraulic fracturing fluid, a flooding fluid, etc. Insome embodiments, the injection solution can be included in a hydraulicfracturing fluid (e.g., the injection solution can be one component ofthe hydraulic fracturing fluid and proppants can be another component ofthe hydraulic fracturing fluid), included in a flooding fluid, etc. Thewater for the injection streams (slugs) may be surface water, waterrecovered from a production well (produced water), sea water, or anysynthetic water, for example. The water may comprise salt, monovalentcations, divalent cations, and additional additives. They may be mixedwith the injection mixture prior to, during, or after the mixing of thewater with the polymer suspension to include any of surfactants, alkali,and optional additives.

Of note, the aqueous fluid used herein for making injection solutionscan comprise produced reservoir brine, reservoir brine, sea water, freshwater, produced water, water, saltwater (e.g. water containing one ormore salts dissolved therein), brine, synthetic brine, syntheticseawater brine, or any combination thereof. Generally, the aqueous fluidcan comprise water from any readily available source, provided that itdoes not contain an excess of compounds that may adversely affect othercomponents in the injection solution or render the injection solutionunsuitable for its intended use (e.g., unsuitable for use in an oil andgas operation such as an EOR application or operation). If desired,aqueous fluids obtained from naturally occurring sources can be treatedprior to use. For example, aqueous fluids can be softened (e.g., toreduce the concentration of divalent and trivalent ions in the aqueousfluid) or otherwise treated to adjust their salinity. In certainembodiments, the aqueous fluid can comprise soft brine or hard brine. Incertain embodiments, the aqueous fluid can comprise produced reservoirbrine, reservoir brine, sea water, or a combination thereof. In someembodiments, the aqueous fluid can be selected from any of surfacewater, water recovered from a production well, sea water, syntheticwater, produced reservoir brine, reservoir brine, fresh water, producedwater, water, saltwater (e.g. water containing one or more saltsdissolved therein), brine, synthetic brine, synthetic seawater brine,and mixtures thereof. In one embodiment, the brine may be a syntheticseawater brine as illustrated in Table A.

TABLE A Ions (ppm) Synthetic seawater brine Na+ 10800 K+ 400 Ca++ 410Mg++ 1280 Cl− 19400 TDS 32290

In one embodiment, seawater is used as the aqueous base, since off-shoreproduction facilities tend to have an abundance of seawater available,limited storage space, and transportation costs to and from off-shoresite are typically high. If seawater is used as the aqueous base, it canbe softened prior to the addition of the suspended polymer, therebyremoving any multivalent ions, specifically Mg and Ca.

Surfactants.

In one embodiment, surfactants are used as the water soluble solvent forthe polymer suspension, and no additional surfactant is added. Incertain other embodiments, the injection streams comprise a polymersuspension and one or more additional surfactants to lower theinterfacial tension between the oil and water phase in the reservoir toless than about 10^-2 dyne/cm (for example), thereby recoveringadditional oil by mobilizing and solubilizing oil trapped by capillaryforces.

Examples of surfactants for addition to the polymer suspension include,but are not limited to, anionic surfactants, cationic surfactants,amphoteric surfactants, non-ionic surfactants, or a combination thereof.Anionic surfactants can include sulfates, sulfonates, phosphates, orcarboxylates. Such anionic surfactants are known and described in theart in, for example, U.S. Pat. No. 7,770,641, incorporated herein byreference in its entirety and for all purposes. Examples of specificanionic surfactants include internal olefin sulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy] single sulfonates, alcohol ether[alkoxy]sulfates, and alcohol ether [alkoxy]carboxylates. Examplecationic surfactants include primary, secondary, or tertiary amines, orquaternary ammonium cations. Example amphoteric surfactants includecationic surfactants that are linked to a terminal sulfonate orsulfonate group. Example non-ionic surfactants include other alcoholalkoxylates such as alkylaryl alkoxy alcohols or alkyl alkoxy alcohols.Other non-ionic surfactants can include alkyl alkoxylated esters andalkyl polyglycosides. In some embodiments, multiple non-ionicsurfactants such as non-ionic alcohols or non-ionic esters are combined.As a skilled artisan may appreciate, the surfactant(s) selection mayvary depending upon such factors as salinity, temperature, and claycontent in the reservoir. The surfactants can be injected in any mannersuch as continuously or in a batch process.

Alkali.

Depending on the type of reservoir, alkali may be included in thepolymer flood, making it an alkali-polymer (AP) flood or analkali-surfactant-polymer (ASP) flood. In one embodiment, the alkaliemployed is a basic salt of an alkali metal from Group IA metals of thePeriodic Table. In another embodiment, the composition comprises thepolymer suspension, a multicarboxylate and one or more alkali metals.Certain embodiments of the disclosure are a method of using acomposition comprising a multicarboxylate and one or more alkali metalsin an enhanced oil recovery process. In an embodiment, the alkali metalsalt is a base, such as an alkali metal hydroxide, carbonate orbicarbonate, including, but not limited to, sodium carbonate, sodiumbicarbonate, sodium hydroxide, potassium hydroxide, sodium silicate,tetrasodium EDTA, sodium metaborate, sodium citrate, and sodiumtetraborate. The alkali may be used in amounts ranging from about 0.3 toabout 5.0 weight percent of the injection fluid, such as about 0.5 toabout 3 weight percent. Use of the alkali maintains surfactant in a highpH environment, which can minimize surfactant adsorption. Alkali canalso protect the surfactant from hardness. Using alkali before and afteran ASP slug can help to minimize surfactant adsorption, as a high pHenvironment is maintained through any diffusion of an ASP slug.

Additional Additives.

The injection slugs (or injection fluid) in one embodiment compriseadditional additives. Examples include chelators, co-solvents, reducingagents/oxygen scavengers, and biocides. Chelators may be used to complexwith multivalent cations and soften the water in the injection fluid.Examples of chelators include ethylenediaminetetraacetic acid (EDTA)which can also be used as an alkali, methylglycinediacetic acid (MGDA).Chelants may be utilized to handle hard brines. The amount of chelantmay be selected based on the amount of divalent ions in the slugs. Forexample, chelating agents can be used a 10:1 molar ratio with divalentcations such as calcium or magnesium.

Co-solvents may also be included in the injection fluid containing thepolymer suspension. Suitable co-solvents are alcohols, such as lowercarbon chain alcohols like isopropyl alcohol, ethanol, n-propyl alcohol,n-butyl alcohol, sec-butyl alcohol, n-amyl alcohol, sec-amyl alcohol,n-hexyl alcohol, sec-hexyl alcohol and the like; alcohol ethers,polyalkylene alcohol ethers, polyalkylene glycols,poly(oxyalkylene)glycols, poly(oxyalkylene)glycols ethers or any othercommon organic co-solvent or combinations of any two or moreco-solvents. For example, in an embodiment, an ether, ethylene glycolbutyl ether (EGBE), is used and may be about 0.75 to 1.5 times theconcentration of surfactant of ASP slug 21. Co-solvents, when used, maybe present in an amount of about 0.5 to about 6.0 weight percent of theinjection fluid, such as from about 0.5 to about 4.0 weight percent, orabout 0.5 to about 3 weight percent.

Reducing agents/oxygen scavengers such as sodium dithionite may be usedto remove any oxygen in the mixture and reduce any free iron into Fe2+.They can be used to protect synthetic polymers from reactions thatcleave the polymer molecule and lower or remove viscosifying abilities.A reduced environment can also lower surfactant adsorption.

Biocides can be used to prevent organic (algal) growth in facilities,stop sulfate reducing bacteria (SRB) growth which “sour” the reservoirby producing H2S, and are also used to protect biopolymers frombiological life which feed on their sugar-like structures and thereforeremove mobility control. Biocides include aldehydes and quaternaryammonium compounds.

The polymer suspension is added to a sufficient amount for the slug toefficiently sweep the reservoir. The required viscosity is a function ofmobility ratio. Mobility ratio (M) is defined as water (or ASP) relativepermeability divided by oil relative permeability multiplied by oilviscosity divided by water (or ASP) viscosity (krw/kro*μo/μw). Generallya unit mobility ratio, M=1, or lower is desired in an ASP flood. In oneexample, effective amounts of polymer are equal to or less than that ofeach subsequent slug's viscosity in order obtain favorable mobilityratio throughout the entire flood process.

For each reservoir operation, the optimal slug volumes may be determinedprior to injection. For example, the polymer slugs may be injected intothe reservoir in volumes of between 0.05 to 1.0 PV, 0.1 to 0.4 PV, or˜0.1 PV. The necessary slug size can be determined through core floodingexperiments and simulation. The volume of a SP slug may be the equal to,or different from the volume of the chaser. The speed of injection ofthe slugs may also vary depending on the reservoir operations.

EXAMPLES

The following examples are given to illustrate the present invention. Inthe examples, the polymer suspension shows a comparable or even betterhydration, filterability and viscosity yield with conventional polymercompositions prepared from either hydrated powder polymer or commercialoil/water emulsion polymers. However, that the invention is not limitedto the specific conditions or details described in these examples.

Example 1

Samples of a commercially available 20M HPAM polymer in various particlesize distribution from fine, normal, to coarse polymer powders wereprepared using a burr grinder. The samples (fine, normal, and coarse)have normalized weight % distribution for various mesh sizes are shownin Table 1.

TABLE 1 Mess size 16 20 25 40 70 140 200 325 400 Pan Fine — — — 9.5336.06 21.52 10.13 13.38 2.54 6.84 Normal 0.01 0.37 3.00 49.15 38.37 7.001.18 0.35 0.14 0.42 Coarse — 9.83 20.03 43.34 24.23 1.85 0.48 0.58 — —

A number of water-soluble non-ionic surfactants having properties asshown in Table 2 were used as solvent for the polymer samples:

TABLE 2 Specific Cloud Point Structure HLB* Gravity Viscosity (cP) (°C.) Lauryl Alcohol-6.5EO 8 0.95 53 Alcohol Ethoxylate — 1.02 120 @ 25C.  47 TDA-9EO 13 0.977 145 @ 25 C.  58 Alcohol Ethoxylate A 12 1.01 100@ 25 C.  64 Alcohol Ethoxylate B 14 1 120 @ 25 C.  73 Alcohol EthoxylateC 14 1-1.05 80 @ 25 C. 62 C10 Guerbet-7EO 12.5 0.99 70 @ 25 C. 68TDA-5EO 10.5 0.97 24 @ 40 C. 64 TDA-7EO 12 1.0 7.1 @ 40 C.  N/A TDA-9EO13 1.01 41 @ 40 C. 59 TDA-12EO 14.4 1.03 51 @ 40 C. 85

Polymer suspension samples were prepared from the non-ionic surfactantin ratios of polymer to solvent of 40:60 to 60:40. The polymersuspension made of fine powder had better stability than those made ofcoarse powder. However, a polymer suspension could be stabilized by theaddition of small amount of an anionic surfactant, e.g., less than 10wt. %.

Example 2

A polymer suspension was prepared from a 50:50 mixture of a partially(25-30%) hydrolyzed polyacrylamide powder, and a water soluble solventprepared from a mixture of non-ionic surfactants with HLB of >8. Thenon-ionic surfactant mixture contain ethoxylates of alkyl polyethyleneglycol ethers based on the C10-Guerbet alcohol and linear alcoholalkoxylates. The mixture was stirred for about 24 hours. A small amount(<5 wt. %) of an anionic surfactant, sodium dihexyl sulfosuccinate, wasadded to the mixture as a stabilizer. The polymer suspension remainedstable after 24 and 48 hours.

Example 3

Another polymer suspension was prepared from a 50:50 mixture of 20 MHPAM polymer powder and a water soluble solvent prepared from a mixtureof alkoxylated (ethoxylated propoxylated) non-ionic surfactants with HLBof >8. A small amount (<5 wt. %) of sodium dihexyl sulfosuccinateanionic surfactant was added to the mixture as a stabilizer. The mixturewas stirred for 10 minutes for a moderately viscous suspension.

Example 4

A synthetic brine solution was used as base brine. The synthetic brinesolution included the following: Na⁺, Ca²⁺, Mg²⁺, Cl⁻, and TDS of about15,000 ppm.

Example 5

In the comparative examples, two samples of 1% polymer in solution wereprepared from the synthetic brine solution of Example 4 with 100% activepowder polymer and 30% polymer emulsion. Both samples were preparedusing methods known in the art, i.e., intense mixing with specialequipment along the line of polymer slicing unit for the powder polymer,and extensive mixing for at least 48 hours for the polymer emulsion. The1% polymer in solution prepared from powder polymer was hazy inappearance. The 1% polymer prepared from emulsion polymer was milkywhite.

Example 6

The polymer suspension from Example 3 was mixed with the synthetic brinesolution of Example 4 for a concentration of 1% polymer in solution. Thepolymer suspensions were hydrated as quickly as 30 minutes under strongshear stress. The sample (in a beaker) was observed to be crystal clear.

Example 7

The polymer suspension from Example 3 was mixed with the synthetic brinesolution of Example 4 for a concentration of 1% polymer in solution.Samples were prepared with mixing ranging from 30 minutes to 3 days.FIG. 1 shows that 60 minutes hydration (mixing in lab scale) wassufficient enough to get a comparable viscosity with 1% polymer hydratedfrom powder polymer (comparative Example 5).

Example 8

A sample of 2000 ppm polymer in solution was prepared from the 50%polymer suspension of Example 3 in the synthetic brine solution ofExample 4. Comparable polymer solution samples were prepared from thepowder polymer and polymer emulsion samples using methods known in theart. FIG. 2 shows that the polymer suspension shows a comparableviscosity yield with conventional emulsion polymers or commercial powderpolymers.

Example 9

A sample of 2000 ppm HPAM polymer hydrated in a synthetic brine ofExample 4 was prepared from the polymer suspension of Example 3.Comparable polymer samples were prepared from samples of 1% polymerhydrated from powder polymer, and 1% polymer solution prepared fromemulsion polymer. Filtration tests using 5 μm and 1.2 μm membrane at 25°C. and 15 psi were carried out. FIG. 3 shows that the polymer suspensionshows a comparable if not better filterability even after a shorthydration.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained by the present invention. It isnoted that, as used in this specification and the appended claims, thesingular forms “a,” “an,” and “the,” include plural references unlessexpressly and unequivocally limited to one referent.

As used herein, the term “include” and its grammatical variants areintended to be non-limiting, such that recitation of items in a list isnot to the exclusion of other like items that can be substituted oradded to the listed items. The terms “comprises” and/or “comprising,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. Unless otherwise defined, all terms, including technical andscientific terms used in the description, have the same meaning ascommonly understood by one of ordinary skill in the art to which thisinvention belongs.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope is defined bythe claims, and can include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims. All citations referred herein are expressly incorporatedherein by reference. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

For the avoidance of doubt, the present application includes thesubject-matter defined in the following numbered paragraphs:

Claim Set A

Claim 1A: A polymer composition for use in enhancing the production ofoil from a formation, the composition comprising:

a powder polymer having an average molecular weight of 0.5 to 30 MillionDaltons suspended in a water soluble solvent having an HLB of greaterthan or equal to 8 and selected from the group of surfactants, glycolethers, alcohols, co-solvents, and mixtures thereof, at a weight ratioof powder polymer to water soluble solvent ranging from 20:80 to 80:20;and

wherein the polymer composition is substantially anhydrous;

wherein the polymer composition is hydrated in an aqueous fluid for aninjection solution in less than or equal to 4 hours containing a polymerconcentration ranging from 100 ppm to 50,000 ppm and having a filterratio of less than or equal to 1.5 at 15 psi using a 1.2 μm filter.

Claim 2A. The polymer composition of claim 1A, wherein the polymercomposition is hydrated in an aqueous fluid for an injection solution inless than or equal to 2 hours.

Claim 3A. The polymer composition of claim 2A, wherein the polymercomposition is hydrated in an aqueous fluid for an injection solution inless than or equal to 1 hour.

Claim 4A. The polymer composition of claim 1A, wherein the polymercomposition is hydrated in an aqueous fluid for an injection solution inless than or equal to 2 hours and having a filter ratio of less than orequal to 1.2 at 15 psi using a 1.2 μm filter.

Claim 5A. The polymer composition of claim 4A, wherein the polymercomposition is hydrated in an aqueous fluid for an injection solution inless than or equal to ½ hours and having a filter ratio of less than orequal to 1.05 at 15 psi using a 1.2 μm filter.

Claim 6A. The polymer composition of claim 1A, wherein the polymercomposition is hydrated in an aqueous fluid for an injection solution inless than or equal to 4 hours, and having a NTU of less than or equal to20.

Claim 7A. The polymer composition of claim 6A, wherein the polymercomposition is hydrated in an aqueous fluid in less than or equal to 1hour for an injection solution having a NTU of less than or equal to 15.

Claim 8A. The polymer composition of claim 7A, wherein the polymercomposition is hydrated in an aqueous fluid in less than or equal to 1hour for an injection solution having a NTU of less than or equal to 10.

Claim 9A. The polymer composition of claim 1A, wherein the polymercomposition is stable.

Claim 10A. The polymer composition of claim 1A, where the polymercomposition is characterized has having a turbidity decrease of at least25% after the powder polymer is suspended in the water soluble solventfor a period of at least 2 hours.

Claim 11A. The polymer composition of claim 10A, where the polymercomposition is characterized has having a turbidity decrease of at least50% after the powder polymer is suspended in the water soluble solventfor a period of at least 2 hours.

Claim 12A. The polymer composition of claim 11A, where the polymercomposition is characterized has having a turbidity decrease of at least75% after the powder polymer is suspended in the water soluble solventfor a period of at least 2 hours.

Claim 13A. The polymer composition of claim 1A, wherein the polymercomposition is hydrated in an aqueous fluid by mixing a sufficientconcentration of the polymer suspension in an aqueous fluid in a mixingtank or an in-line mixer in less than or equal to 4 hours for aninjection solution containing a polymer concentration ranging from 100ppm to 50,000 ppm.

Claim 14A. The polymer composition of claim 13A, wherein the polymercomposition is hydrated in an aqueous fluid by mixing a sufficientconcentration of the polymer suspension in an aqueous fluid in a mixingtank or an in-line mixer in less than or equal to 2 hours for aninjection solution containing a polymer concentration ranging from 100ppm to 50,000 ppm.

Claim 15A. The polymer composition of claim 14A, wherein the polymercomposition is hydrated in an aqueous fluid by mixing a sufficientconcentration of the polymer suspension in an aqueous fluid in a mixingtank or an in-line mixer in less than or equal to 1 hour for aninjection solution containing a polymer concentration ranging from 100ppm to 50,000 ppm.

Claim 16A. The polymer composition of claim 1A, wherein the polymercomposition is pumpable.

Claim 17A. The polymer composition of claim 16A, wherein the polymercomposition remains pumpable after the powder polymer is suspended inthe water soluble solvent for more than or equal to 24 hours.

Claim 18A. The polymer composition of claim 1A, wherein the powderpolymer is a biopolymer that is a polysaccharide.

Claim 19A. The polymer composition of claim 1A, wherein the powderpolymer is a biopolymer or a synthetic polymer.

Claim 20A. The polymer composition of claim 1A, wherein the powderpolymer is a synthetic polymer selected from the group ofpolyacrylamides, partially hydrolyzed polyacrylamides,hydrophobically-modified associative polymers, 2-acrylamido2-methylpropane sulfonic acid and salts thereof, N-vinyl pyrrolidone,polyacrylic acid, polyvinyl alcohol, and mixtures thereof.

Claim 21A. The polymer composition of claim 1A, wherein the powderpolymer is suspended in a water soluble solvent having an HLB of greaterthan or equal to 8 that comprises a mixture of non-ionic and anionicsurfactants.

Claim 22A. The polymer composition of claim 21A, wherein the anionicsurfactant is present in an amount of less than or equal to 5 wt. % as astabilizer.

Claim 23A. The polymer composition of claim 1A, wherein the watersoluble solvent is selected from isopropyl alcohol (IPA), n-propylalcohol, isobutyl alcohol (IBA), methyl-isobutyl alcohol, secondarybutyl alcohol (SBA), ethylene glycol monobutyl ether, diethylene glycolmonobutyl ether, triethylene glycol monobutyl ether, and mixturesthereof

Claim 24A. The polymer composition of claim 1A, wherein the watersoluble solvent is an ionic surfactant selected from ethoxylatedsurfactants, nonylphenol ethoxylates, alcohol ethoxylates, internalolefin sulfonates, isomerized olefin sulfonates, alkyl aryl sulfonates,medium alcohol (C10 to C17) alkoxy sulfates, alcohol ether[alkoxy]carboxylates, alcohol ether [alkoxy]sulfates, alkyl sulfonate,α-olefin sulfonates (AOS), dihexyl sulfosuccinates, alkylpolyalkoxysulfates, sulfonated amphoteric surfactants, and mixtures thereof.

Claim 25A. The polymer composition of claim 1A, wherein the watersoluble solvent is a co-solvent, wherein the co-solvent is selected fromthe group of an ionic surfactant, non-ionic surfactant, anionicsurfactant, cationic surfactant, nonionic surfactant, amphotericsurfactant, ketones, esters, ethers, glycol ethers, glycol ether esters,lactams, cyclic ureas, alcohols, aromatic hydrocarbons, aliphatichydrocarbons, alicyclic hydrocarbons, nitroalkanes, unsaturatedhydrocarbons, halocarbons, surfactants commonly used for enhanced oilrecovery applications, alkyl aryl sulfonates (AAS), a-olefin sulfonates(AOS), internal olefin sulfonates (IOS), alcohol ether sulfates derivedfrom propoxylated Ci₂-C₂o alcohols, ethoxylated alcohols, mixtures of analcohol and an ethoxylated alcohol, mixtures of anionic and cationicsurfactants, disulfonated surfactants, aromatic ether polysulfonates,isomerized olefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10to C17) alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcoholether [alkoxy]sulfates, primary amines, secondary amines, tertiaryamines, quaternary ammonium cations, cationic surfactants that arelinked to a terminal sulfonate or carboxylate group, alkyl aryl alkoxyalcohols, alkyl alkoxy alcohols, alkyl alkoxylated esters, alkylpolyglycosides, alkoxy ethoxyethanol compounds, isobutoxy ethoxyethanol(“iBDGE”), n-pentoxy ethoxyethanol (“n-PDGE”), 2-methylbutoxyethoxyethanol (“2-MBDGE”), methylbutoxy ethoxyethanol (“3-MBDGE”),(3,3-dimethylbutoxy ethoxyethanol (“3,3-DMBDGE”), cyclohexylmethyleneoxyethoxyethanol (hereafter “CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol(“MIBCDGE”), n-hexoxy ethoxyethanol (hereafter “n-HDGE”),4-methylpentoxy ethoxyethanol (“4-MPDGE”), butoxy ethanol, propoxyethanol, hexoxy ethanol, isoproproxy 2-propanol, butoxy 2-propanol,propoxy 2-propanol, tertiary butoxy 2-propanol, ethoxy ethanol, butoxyethoxy ethanol, propoxy ethoxy ethanol, hexoxy ethoxy ethanol, methoxyethanol, methoxy 2-propanol and ethoxy ethanol, n-methyl-2-pyrrolidone,dimethyl ethylene urea, and mixtures thereof.

Claim 26A. A polymer composition for use in enhancing the production ofoil from a formation, the composition consisting essentially of a powderpolymer having an average molecular weight of 0.5 to 30 Million Daltonsselected from the group of polyacrylamides, partially hydrolyzedpolyacrylamides, hydrophobically-modified associative polymers,2-acrylamido 2-methylpropane sulfonic acid and salts thereof, N-vinylpyrrolidone, biopolymers, synthetic polymers, polyacrylic acid,polyvinyl alcohol, and mixtures thereof; suspended in a water solublesolvent having an HLB of greater than or equal to 8 and selected fromthe group of surfactants, glycol ethers, alcohols, co-solvents, andmixtures thereof; at a weight ratio of powder polymer to water solublesolvent ranging from 30:70 to 70:30;

wherein the polymer composition is substantially anhydrous; and

wherein the polymer composition is hydrated in an aqueous fluid in lessthan or equal to 4 hours for an injection solution containing a polymerconcentration ranging from 100 ppm to 50,000 ppm and having a filterratio of less than or equal to 1.5 at 15 psi using a 1.2 μm filter.

Claim Set B

Claim 1B. A method of enhancing oil recovery in a subterraneanreservoir, the method comprising

providing a wellbore in fluid communication with the subterraneanreservoir;

providing a polymer suspension, wherein the polymer suspension comprisesa powder polymer having an average molecular weight of 0.5 to 30 MillionDaltons suspended in a water soluble solvent having an HLB of greaterthan or equal to 8 and selected from the group of surfactants, glycolethers, alcohols, co-solvents, and mixtures thereof, at a weight ratioof powder polymer to water soluble solvent ranging from 20:80 to 80:20;wherein the polymer suspension is substantially anhydrous;

providing an aqueous fluid selected from any of surface water, waterrecovered from a production well, sea water, synthetic water, producedreservoir brine, reservoir brine, fresh water, produced water, water,saltwater, brine, synthetic brine, synthetic seawater brine, andmixtures thereof;

mixing a sufficient amount of the polymer suspension in the aqueousfluid for the polymer to be hydrated resulting an injection solution inless than or equal to 4 hours, the injection solution containing apolymer concentration ranging from 100 ppm to 50,000 ppm and having afilter ratio of less than 1.5 at 15 psi using a 1.2 μm filter;

injecting the injection solution into the wellbore into the subterraneanreservoir.

Claim 2B. The method of claim 1B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid is via a mixingtank or an in-line mixer.

Claim 3B. The method of claim 1B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid for the polymer tobe hydrated resulting in an injection solution in less than or equal to2 hours.

Claim 4B. The method of claim 3B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid for the polymer tobe hydrated resulting in an injection solution in less than or equal to1 hour.

Claim 5B. The method of claim 1B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting in aninjection solution having a filter ratio of less than or equal to 1.2 at15 psi using a 1.2 μm filter.

Claim 6B. The method of claim 5B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting in aninjection solution having a filter ratio of less than or equal to 1.05at 15 psi using a 1.2 μm filter.

Claim 7B. The method of claim 1B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting in aninjection solution having a NTU of less than or equal to 20.

Claim 8B. The method of claim 7B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting in aninjection solution having a NTU of less than or equal to 15.

Claim 9B. The method of claim 8B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting in aninjection solution having a NTU of less than or equal to 10.

Claim 10B. The method of claim 1B, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 25%.

Claim 11B. The method of claim 10B, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 50%.

Claim 12B. The method of claim 11B, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 75%.

Claim 13B. The method of claim 1B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid is for less thanor equal to 2 hours for an injection solution.

Claim 14B. The method of claim 13B, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid is for less thanor equal to 1 hour for an injection solution.

Claim 15B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent for less than or equal to 24 hours, for a stable andsubstantially anhydrous polymer suspension.

Claim 16B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the powder polymer is a biopolymer that is apolysaccharide.

Claim 17B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the powder polymer is a biopolymer or a syntheticpolymer.

Claim 18B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the powder polymer is a synthetic polymer selectedfrom the group of polyacrylamides, partially hydrolyzed polyacrylamides,hydrophobically-modified associative polymers, 2-acrylamido2-methylpropane sulfonic acid and salts thereof, N-vinyl pyrrolidone,polyacrylic acid, polyvinyl alcohol, and mixtures thereof.

Claim 19B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the water soluble solvent comprises a mixture ofnon-ionic and anionic surfactants.

Claim 20B. The method of claim 19B, wherein the anionic surfactant ispresent in an amount of less than or equal to 5 wt. % as a stabilizer.

Claim 21B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the water soluble solvent is selected from isopropylalcohol (IPA), n-propyl alcohol, isobutyl alcohol (IBA), methyl-isobutylalcohol, secondary butyl alcohol (SBA), ethylene glycol monobutyl ether,diethylene glycol monobutyl ether, triethylene glycol monobutyl ether,and mixtures thereof

Claim 22B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the water soluble solvent is selected fromethoxylated surfactants, nonylphenol ethoxylates, alcohol ethoxylates,internal olefin sulfonates, isomerized olefin sulfonates, alkyl arylsulfonates, medium alcohol (C10 to C17) alkoxy sulfates, alcohol ether[alkoxy]carboxylates, alcohol ether [alkoxy]sulfates, alkyl sulfonate,α-olefin sulfonates (AOS), dihexyl sulfosuccinates, alkylpolyalkoxysulfates, sulfonated amphoteric surfactants, and mixtures thereof

Claim 23B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the water soluble solvent is a co-solvent selectedfrom the group of an ionic surfactant, non-ionic surfactant, anionicsurfactant, cationic surfactant, nonionic surfactant, amphotericsurfactant, ketones, esters, ethers, glycol ethers, glycol ether esters,lactams, cyclic ureas, alcohols, aromatic hydrocarbons, aliphatichydrocarbons, alicyclic hydrocarbons, nitroalkanes, unsaturatedhydrocarbons, halocarbons, surfactants commonly used for enhanced oilrecovery applications, alkyl aryl sulfonates (AAS), a-olefin sulfonates(AOS), internal olefin sulfonates (IOS), alcohol ether sulfates derivedfrom propoxylated Ci₂-C₂o alcohols, ethoxylated alcohols, mixtures of analcohol and an ethoxylated alcohol, mixtures of anionic and cationicsurfactants, disulfonated surfactants, aromatic ether polysulfonates,isomerized olefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10to C17) alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcoholether [alkoxy]sulfates, primary amines, secondary amines, tertiaryamines, quaternary ammonium cations, cationic surfactants that arelinked to a terminal sulfonate or carboxylate group, alkyl aryl alkoxyalcohols, alkyl alkoxy alcohols, alkyl alkoxylated esters, alkylpolyglycosides, alkoxy ethoxyethanol compounds, isobutoxy ethoxyethanol(“iBDGE”), n-pentoxy ethoxyethanol (“n-PDGE”), 2-methylbutoxyethoxyethanol (“2-MBDGE”), methylbutoxy ethoxyethanol (“3-MBDGE”),(3,3-dimethylbutoxy ethoxyethanol (“3,3-DMBDGE”), cyclohexylmethyleneoxyethoxyethanol (hereafter “CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol(“MIBCDGE”), n-hexoxy ethoxyethanol (hereafter “n-HDGE”),4-methylpentoxy ethoxyethanol (“4-MPDGE”), butoxy ethanol, propoxyethanol, hexoxy ethanol, isoproproxy 2-propanol, butoxy 2-propanol,propoxy 2-propanol, tertiary butoxy 2-propanol, ethoxy ethanol, butoxyethoxy ethanol, propoxy ethoxy ethanol, hexoxy ethoxy ethanol, methoxyethanol, methoxy 2-propanol and ethoxy ethanol, n-methyl-2-pyrrolidone,dimethyl ethylene urea, and mixtures thereof

Claim 24B. The method of claim 1B, wherein providing the polymersuspension comprises mixing the powder polymer into the water solublesolvent and wherein the weight ratio of powder polymer to water solublesolvent ranges from 30:70 to 70:30.

Claim 25B. The method of claim 24B, wherein the weight ratio of powderpolymer to water soluble solvent ranges from 40:60 to 60:40.

Claim 26B. The method of claim 1B, wherein the wellbore is an injectionwellbore associated with an injection well, and the method furthercomprising:

providing a production well spaced apart from the injection well apredetermined distance and having a production wellbore in fluidcommunication with the subterranean reservoir,

wherein the injection of the injection solution increases flow ofhydrocarbons to the production wellbore.

Claim 27B. The method of claim 1B, wherein the wellbore is a hydraulicfracturing wellbore associated with a hydraulic fracturing well.

Claim 28B. The method of claim 1B, wherein the injection solutionfunctions as a drag reducer.

Claim 29B. The method of claim 1B, wherein the injection solution isincluded in a hydraulic fracturing fluid.

Claim 30B. The method of claim 1B, wherein the injection solution isused as a hydraulic fracturing fluid.

Claim 31B. A method of enhancing oil recovery in a subterraneanreservoir, the method comprising injecting an injection solution intothe subterranean reservoir, whereby the injection solution is preparedby

mixing a powder polymer having an average molecular weight about 0.5 to30 Million Daltons with a water soluble solvent having an HLB of greaterthan or equal to 8 at a weight ratio of powder polymer to water solublesolvent ranging from 20:80 to 80:20, generating a stable andsubstantially anhydrous polymer suspension; the water soluble solvent isselected from the group of surfactants, glycol ethers, alcohols,co-solvents, and mixtures thereof; the powder polymer is selected fromthe group of polyacrylamides, partially hydrolyzed polyacrylamides,hydrophobically-modified associative polymers, 2-acrylamido2-methylpropane sulfonic acid and salts thereof, N-vinyl pyrrolidone,polyacrylic acid, polyvinyl alcohol, biopolymers, synthetic polymers,and mixtures thereof;

mixing a sufficient amount of the polymer suspension into an aqueousfluid for the polymer to be hydrated resulting in an injection solutioncontaining a polymer concentration ranging from 100 ppm to 50,000 ppm inless than or equal to 4 hours;

wherein the injection solution has a filter ratio of less than or equalto 1.5 at 15 psi using a 1.2 μm filter and a NTU of less than or equalto 20.

Claim Set N

Claim 1N. An injection solution for injecting into a subterraneanreservoir to enhance production and recovery of oil from the reservoir,the injection solution is prepared by mixing a sufficient amount of apumpable, stable and substantially anhydrous polymer suspension in anaqueous fluid for the polymer to be hydrated in less than or equal to 4hours, resulting in the injection solution containing a polymerconcentration ranging from 100 ppm to 50,000 ppm; the injection solutionhas a filter ratio of less than or equal to 1.5 at 15 psi using a 1.2 μmfilter;

wherein the polymer suspension comprises a powder polymer having anaverage molecular weight of 0.5 to 30 Million Daltons suspended in awater soluble solvent having an HLB of greater than or equal to 8 andselected from the group of surfactants, glycol ethers, alcohols,co-solvents, and mixtures thereof, at a weight ratio of powder polymerto water soluble solvent ranging from 20:80 to 80:20;

wherein the aqueous fluid selected from any of surface water, waterrecovered from a production well, sea water, synthetic water, producedreservoir brine, reservoir brine, fresh water, produced water, water,saltwater, brine, synthetic brine, synthetic seawater brine, andmixtures thereof

Claim 2N. The injection solution of claim 1N, wherein the water solublesolvent comprises a mixture of non-ionic and anionic surfactants.

Claim 3N. The injection solution of claim 1N, wherein the powder polymeris a biopolymer that is a polysaccharide.

Claim 4N. The injection solution of claim 1N, wherein the powder polymeris a biopolymer or a synthetic polymer.

Claim 5N. The injection solution of claim 1N, wherein the powder polymeris a synthetic polymer selected from the group of polyacrylamides,partially hydrolyzed polyacrylamides, hydrophobically-modifiedassociative polymers, 2-acrylamido 2-methylpropane sulfonic acid andsalts thereof, N-vinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol,and mixtures thereof.

Claim 6N. The injection solution of claim 1N, wherein the water solublesolvent is selected from isopropyl alcohol (IPA), n-propyl alcohol,isobutyl alcohol (IBA), methyl-isobutyl alcohol, secondary butyl alcohol(SBA), ethylene glycol monobutyl ether, diethylene glycol monobutylether, triethylene glycol monobutyl ether, and mixtures thereof.

Claim 7N. The injection solution of claim 1N, wherein the water solublesolvent is selected from ethoxylated surfactants, nonylphenolethoxylates, alcohol ethoxylates, internal olefin sulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, alkyl sulfonate, α-olefin sulfonates (AOS), dihexylsulfosuccinates, alkylpolyalkoxy sulfates, sulfonated amphotericsurfactants, and mixtures thereof.

Claim 8N. The injection solution of claim 1N, wherein the water solublesolvent is a co-solvent selected from the group of an ionic surfactant,non-ionic surfactant, anionic surfactant, cationic surfactant, nonionicsurfactant, amphoteric surfactant, ketones, esters, ethers, glycolethers, glycol ether esters, lactams, cyclic ureas, alcohols, aromatichydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons,nitroalkanes, unsaturated hydrocarbons, halocarbons, surfactantscommonly used for enhanced oil recovery applications, alkyl arylsulfonates (AAS), a-olefin sulfonates (AOS), internal olefin sulfonates(IOS), alcohol ether sulfates derived from propoxylated Ci₂-C₂oalcohols, ethoxylated alcohols, mixtures of an alcohol and anethoxylated alcohol, mixtures of anionic and cationic surfactants,disulfonated surfactants, aromatic ether polysulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, primary amines, secondary amines, tertiary amines,quaternary ammonium cations, cationic surfactants that are linked to aterminal sulfonate or carboxylate group, alkyl aryl alkoxy alcohols,alkyl alkoxy alcohols, alkyl alkoxylated esters, alkyl polyglycosides,alkoxy ethoxyethanol compounds, isobutoxy ethoxyethanol (“iBDGE”),n-pentoxy ethoxyethanol (“n-PDGE”), 2-methylbutoxy ethoxyethanol(“2-MBDGE”), methylbutoxy ethoxyethanol (“3-MBDGE”), (3,3-dimethylbutoxyethoxyethanol (“3,3-DMBDGE”), cyclohexylmethyleneoxy ethoxyethanol(hereafter “CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol (“MIBCDGE”),n-hexoxy ethoxyethanol (hereafter “n-HDGE”), 4-methylpentoxyethoxyethanol (“4-MPDGE”), butoxy ethanol, propoxy ethanol, hexoxyethanol, isoproproxy 2-propanol, butoxy 2-propanol, propoxy 2-propanol,tertiary butoxy 2-propanol, ethoxy ethanol, butoxy ethoxy ethanol,propoxy ethoxy ethanol, hexoxy ethoxy ethanol, methoxy ethanol, methoxy2-propanol and ethoxy ethanol, n-methyl-2-pyrrolidone, dimethyl ethyleneurea, and mixtures thereof

Claim 9N. The injection solution of claim 1N, wherein the water solublesolvent comprises a mixture of non-ionic and anionic surfactants, andwherein the anionic surfactant is present in an amount of less than orequal to 5 wt. % as a stabilizer.

Claim 10N. The injection solution of claim 1N, wherein the polymersuspension comprises a powder polymer suspended in a water solublesolvent at a weight ratio of powder polymer to water soluble solventranging from 30:70 to 70:30.

Claim 11N. The injection solution of claim 10N, wherein the polymersuspension comprises a powder polymer suspended in a water solublesolvent at a weight ratio of powder polymer to water soluble solventranging from 40:60 to 60:40.

Claim 12N. The injection solution of claim 1N, wherein the injectionsolution is prepared by mixing the pumpable, stable and substantiallyanhydrous polymer suspension in an aqueous fluid in less than or equalto 2 hours.

Claim 13N. The injection solution of claim 12N, wherein the injectionsolution is prepared by mixing the pumpable, stable and substantiallyanhydrous polymer suspension in an aqueous fluid in less than or equalto 1 hour.

Claim 14N. The injection solution of claim 1N, wherein the injectionsolution is prepared by mixing the pumpable, stable and substantiallyanhydrous polymer suspension in a mixing tank or via an in-line staticmixer.

Claim 15N. The injection solution of claim 1N, wherein the injectionsolution has a filter ratio of less than or equal to 1.2 at 15 psi usinga 1.2 μm filter.

Claim 16N. The injection solution of claim 1N, wherein the injectionsolution has a NTU of less than or equal to 20.

Claim 17N. The injection solution of claim 16N, wherein the injectionsolution has a NTU of less than or equal to 15.

Claim 18N. The injection solution of claim 17N, wherein the injectionsolution has a NTU of less than or equal to 10.

Claim 19N. The injection solution of claim 1N, wherein after the powderpolymer is suspended in the water soluble solvent for a period of atleast 2 hours with a turbidity decrease of at least 25%.

Claim 20N. The injection solution of claim 19N, wherein after the powderpolymer is suspended in the water soluble solvent for a period of atleast 2 hours with a turbidity decrease of at least 50%.

Claim 21N. The injection solution of claim 20N, wherein after the powderpolymer is suspended in the water soluble solvent for a period of atleast 2 hours with a turbidity decrease of at least 75%.

Claim 22N. The injection solution of claim 1N, wherein the polymer inthe injection solution has an average particle size ranging from 0.01 to10 μm.

Claim Set C

Claim 1C. A method for making a polymer suspension for use in enhancingthe production of oil from a formation, the method comprising

mixing a powder polymer having an average molecular weight of 0.5 to 30Million Daltons into a water soluble solvent having an HLB of greaterthan or equal to 8 for less than or equal to 24 hours,

the water soluble solvent is selected from the group of surfactants,glycol ethers, alcohols, co-solvents, and mixtures thereof, at a weightratio of powder polymer to water soluble solvent ranging from 20:80 to80:20;

wherein the polymer suspension is stable, pumpable, and substantiallyanhydrous; and

wherein the polymer suspension is hydrated for an injection solution inless than or equal to 4 hours, containing a polymer concentrationranging from 100 ppm to 50,000 ppm and having a filter ratio of lessthan or equal to 1.5 at 15 psi using a 1.2 μm filter, by mixing asufficient amount of the polymer suspension in an aqueous fluid.

Claim 2C. The method of claim 1C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid is via a mixingtank or an in-line mixer.

Claim 3C. The method of claim 1C, wherein the polymer suspension ishydrated in less than or equal to 2 hours by mixing of a sufficientamount of the polymer suspension in the aqueous fluid.

Claim 4C. The method of claim 3C, wherein the polymer suspension ishydrated in less than or equal to 1 hours by mixing of a sufficientamount of the polymer suspension in the aqueous fluid.

Claim 5C. The method of claim 1C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting aninjection solution having a filter ratio of less than or equal to 1.2 at15 psi using a 1.2 μm filter.

Claim 6C. The method of claim 5C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting aninjection solution having a filter ratio of less than or equal to 1.05at 15 psi using a 1.2 μm filter.

Claim 7C. The method of claim 1C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting aninjection solution having a NTU of less than or equal to 20.

Claim 8C. The method of claim 7C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting aninjection solution having a NTU of less than or equal to 15.

Claim 9C. The method of claim 8C, wherein the mixing of a sufficientamount of the polymer suspension in the aqueous fluid resulting aninjection solution having a NTU of less than or equal to 10.

Claim 10C. The method of claim 1C, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 25%.

Claim 11C. The method of claim 10C, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 50%.

Claim 12C. The method of claim 11C, wherein after the powder polymer issuspended in the water soluble solvent for a period of at least 2 hourswith a turbidity decrease of at least 75%.

Claim 13C. The method of claim 1C, wherein the mixing of the powderpolymer having an average molecular weight of 0.5 to 30 Million Daltonsinto the water soluble solvent having an HLB greater than or equal to 8is for less than or equal to 4 hours.

Claim 14C. The method of claim 13C, wherein the mixing of the powderpolymer having an average molecular weight of 0.5 to 30 Million Daltonsinto the water soluble solvent having an HLB greater than or equal to 8is for less than or equal to 2 hour.

Claim 15C. The method of claim 14C, wherein the mixing of the powderpolymer having an average molecular weight of 0.5 to 30 Million Daltonsinto the water soluble solvent having an HLB greater than or equal to 8is for less than or equal to 1 hour.

Claim 16C. The method of claim 1C, wherein providing the powder polymeris a biopolymer that is a polysaccharides.

Claim 17C. The method of claim 1C, wherein providing the powder polymeris a biopolymer or a synthetic polymer.

Claim 18C. The method of claim 1C, wherein the powder polymer is asynthetic polymer selected from the group of polyacrylamides, partiallyhydrolyzed polyacrylamides, hydrophobically-modified associativepolymers, 2-acrylamido 2-methylpropane sulfonic acid and salts thereof,N-vinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol, and mixturesthereof.

Claim 19C. The method of claim 1C, wherein water soluble solvent isselected from isopropyl alcohol (IPA), n-propyl alcohol, isobutylalcohol (IBA), methyl-isobutyl alcohol, secondary butyl alcohol (SBA),ethylene glycol monobutyl ether, diethylene glycol monobutyl ether,triethylene glycol monobutyl ether, and mixtures thereof.

20C. The method of claim 1C, wherein the water soluble solvent is anionic surfactant selected from ethoxylated surfactants, nonylphenolethoxylates, alcohol ethoxylates, internal olefin sulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, alkyl sulfonate, α-olefin sulfonates (AOS), dihexylsulfosuccinates, alkylpolyalkoxy sulfates, sulfonated amphotericsurfactants, and mixtures thereof.

Claim 21C. The method of claim 1, wherein the water soluble solvent is aco-solvent selected from the group of an ionic surfactant, non-ionicsurfactant, anionic surfactant, cationic surfactant, nonionicsurfactant, amphoteric surfactant, ketones, esters, ethers, glycolethers, glycol ether esters, lactams, cyclic ureas, alcohols, aromatichydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons,nitroalkanes, unsaturated hydrocarbons, halocarbons, surfactantscommonly used for enhanced oil recovery applications, alkyl arylsulfonates (AAS), a-olefin sulfonates (AOS), internal olefin sulfonates(IOS), alcohol ether sulfates derived from propoxylated Ci₂-C₂oalcohols, ethoxylated alcohols, mixtures of an alcohol and anethoxylated alcohol, mixtures of anionic and cationic surfactants,disulfonated surfactants, aromatic ether polysulfonates, isomerizedolefin sulfonates, alkyl aryl sulfonates, medium alcohol (C10 to C17)alkoxy sulfates, alcohol ether [alkoxy]carboxylates, alcohol ether[alkoxy]sulfates, primary amines, secondary amines, tertiary amines,quaternary ammonium cations, cationic surfactants that are linked to aterminal sulfonate or carboxylate group, alkyl aryl alkoxy alcohols,alkyl alkoxy alcohols, alkyl alkoxylated esters, alkyl polyglycosides,alkoxy ethoxyethanol compounds, isobutoxy ethoxyethanol (“iBDGE”),n-pentoxy ethoxyethanol (“n-PDGE”), 2-methylbutoxy ethoxyethanol(“2-MBDGE”), methylbutoxy ethoxyethanol (“3-MBDGE”), (3,3-dimethylbutoxyethoxyethanol (“3,3-DMBDGE”), cyclohexylmethyleneoxy ethoxyethanol(hereafter “CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol (“MIBCDGE”),n-hexoxy ethoxyethanol (hereafter “n-HDGE”), 4-methylpentoxyethoxyethanol (“4-MPDGE”), butoxy ethanol, propoxy ethanol, hexoxyethanol, isoproproxy 2-propanol, butoxy 2-propanol, propoxy 2-propanol,tertiary butoxy 2-propanol, ethoxy ethanol, butoxy ethoxy ethanol,propoxy ethoxy ethanol, hexoxy ethoxy ethanol, methoxy ethanol, methoxy2-propanol and ethoxy ethanol, n-methyl-2-pyrrolidone, dimethyl ethyleneurea, and mixtures thereof

Claim 22C. The method of claim 1C, wherein the water soluble solventcomprises a mixture of non-ionic and anionic surfactants.

Claim 23C. The method of claim 22C, wherein the anionic surfactant ispresent in an amount of less than or equal to 5 wt. % as a stabilizer.

Claim 24C. The method of claim 1C, wherein the weight ratio of powderpolymer to water soluble solvent ranges from 30:70 to 70:30.

Claim 25C. The method of claim 24C, wherein the weight ratio of powderpolymer to water soluble solvent ranges from 40:60 to 60:40.

Claim 26C. The method of claim 1C, wherein the polymer suspension ishydrated in less than or equal to 4 hours for an injection solutioncontaining has an average particle size ranging from 0.01 to 10 μm.

The invention claimed is:
 1. An injection solution for injecting into asubterranean reservoir to enhance production and recovery of oil fromthe reservoir, the injection solution is prepared by mixing a sufficientamount of a pumpable and stable polymer suspension containing less thanor equal to 3 wt. % water in an aqueous fluid for the polymer to behydrated in less than or equal to 4 hours, resulting in the injectionsolution containing a polymer concentration ranging from 100 ppm to50,000 ppm; the injection solution has a filter ratio of less than orequal to 1.5 at 15 psi using a 1.2 μm filter; wherein the polymersuspension comprises a powder polymer having an average molecular weightof 0.5 to 30 Million Daltons suspended in a water soluble solvent at aweight ratio of powder polymer to water soluble solvent ranging from20:80 to 80:20, wherein the water soluble solvent has a HLB of greaterthan or equal to 8 and comprises a mixture of non-ionic and anionicsurfactants; wherein the aqueous fluid selected from any of surfacewater, water recovered from a production well, sea water, syntheticwater, produced reservoir brine, reservoir brine, fresh water, producedwater, water, saltwater, brine, synthetic brine, synthetic seawaterbrine, and mixtures thereof.
 2. The injection solution of claim 1,wherein the powder polymer is a biopolymer that is a polysaccharide. 3.The injection solution of claim 1, wherein the powder polymer is abiopolymer or a synthetic polymer.
 4. The injection solution of claim 1,wherein the powder polymer is a synthetic polymer selected from thegroup of polyacrylamides, partially hydrolyzed polyacrylamides,hydrophobically-modified associative polymers, copolymers ofpolyacrylamide and one or both of 2-acrylamido 2-methylpropane sulfonicacid and salts thereof and N-vinyl pyrrolidone, single-, co-, orter-polymers of N-vinyl pyrrolidones, polyacrylic acid, polyvinylalcohol, and mixtures thereof.
 5. The injection solution of claim 1,wherein the water soluble solvent further comprises isopropyl alcohol(IPA), n-propyl alcohol, isobutyl alcohol (IBA), methyl-isobutylalcohol, secondary butyl alcohol (SBA), ethylene glycol monobutyl ether,diethylene glycol monobutyl ether, triethylene glycol monobutyl ether,and mixtures thereof.
 6. The injection solution of claim 1, wherein thewater soluble solvent is selected from ethoxylated surfactants,nonylphenol ethoxylates, alcohol ethoxylates, internal olefinsulfonates, isomerized olefin sulfonates, alkyl aryl sulfonates, mediumalcohol (C10 to C17) alkoxy sulfates, alcohol ether[alkoxy]carboxylates, alcohol ether [alkoxy]sulfates, alkyl sulfonate,a-olefin sulfonates (AOS), dihexyl sulfosuccinates, alkylpolyalkoxysulfates, sulfonated amphoteric surfactants, and mixtures thereof. 7.The injection solution of claim 1, wherein the water soluble solventfurther comprises a co-solvent, wherein the co-solvent is selected fromthe group of an ionic surfactant, non-ionic surfactant, anionicsurfactant, cationic surfactant, nonionic surfactant, amphotericsurfactant, ketones, esters, ethers, glycol ethers, glycol ether esters,lactams, cyclic ureas, alcohols, aromatic hydrocarbons, aliphatichydrocarbons, alicyclic hydrocarbons, nitroalkanes, unsaturatedhydrocarbons, halocarbons, alkyl aryl sulfonates (AAS), a-olefinsulfonates (AOS), internal olefin sulfonates (IOS), alcohol ethersulfates derived from propoxylated Ci₂-C₂o alcohols, ethoxylatedalcohols, mixtures of an alcohol and an ethoxylated alcohol, mixtures ofanionic and cationic surfactants, disulfonated surfactants, aromaticether polysulfonates, isomerized olefin sulfonates, alkyl arylsulfonates, medium alcohol (C10 to C17) alkoxy sulfates, alcohol ether[alkoxy]carboxylates, alcohol ether [alkoxy]sulfates, primary amines,secondary amines, tertiary amines, quaternary ammonium cations, cationicsurfactants that are linked to a terminal sulfonate or carboxylategroup, alkyl aryl alkoxy alcohols, alkyl alkoxy alcohols, alkylalkoxylated esters, alkyl polyglycosides, alkoxy ethoxyethanolcompounds, isobutoxy ethoxyethanol (“iBDGE”), n-pentoxy ethoxyethanol(“n-PDGE”), 2-methylbutoxy ethoxyethanol (“2-MBDGE”), methylbutoxyethoxyethanol (“3-MBDGE”), (3,3-dimethylbutoxy ethoxyethanol(“3,3-DMBDGE”), cyclohexylmethyleneoxy ethoxyethanol (hereafter“CHMDGE”), 4-Methylpent-2-oxy ethoxyethanol (“MIBCDGE”), n-hexoxyethoxyethanol (hereafter “n-HDGE”), 4-methylpentoxy ethoxyethanol(“4-MPDGE”), butoxy ethanol, propoxy ethanol, hexoxy ethanol,isoproproxy 2-propanol, butoxy 2-propanol, propoxy 2-propanol, tertiarybutoxy 2-propanol, ethoxy ethanol, butoxy ethoxy ethanol, propoxy ethoxyethanol, hexoxy ethoxy ethanol, methoxy ethanol, methoxy 2-propanol andethoxy ethanol, n-methyl-2-pyrrolidone, dimethyl ethylene urea, andmixtures thereof.
 8. The injection solution of claim 1, wherein theanionic surfactant is present in an amount of less than or equal to 5wt. % as a stabilizer.
 9. The injection solution of claim 1, wherein thepolymer suspension comprises a powder polymer suspended in a watersoluble solvent at a weight ratio of powder polymer to water solublesolvent ranging from 30:70 to 70:30.
 10. The injection solution of claim9, wherein the polymer suspension comprises a powder polymer suspendedin a water soluble solvent at a weight ratio of powder polymer to watersoluble solvent ranging from 40:60 to 60:40.
 11. The injection solutionof claim 1, wherein the injection solution is prepared by mixing thepumpable and stable polymer suspension containing less than or equal to3 wt. % water in an aqueous fluid in less than or equal to 2 hours. 12.The injection solution of claim 11, wherein the injection solution isprepared by mixing the pumpable and stable polymer suspension containingless than or equal to 3 wt. % water in an aqueous fluid in less than orequal to 1 hour.
 13. The injection solution of claim 1, wherein theinjection solution is prepared by mixing the pumpable and stable polymersuspension containing less than or equal to 3 wt. % water in a mixingtank or via an in-line static mixer.
 14. The injection solution of claim1, wherein the injection solution has a filter ratio of less than orequal to 1.2 at 15 psi using a 1.2 μm filter.
 15. The injection solutionof claim 1, wherein the injection solution has a turbidity of less thanor equal to 20 NTU.
 16. The injection solution of claim 15, wherein theinjection solution has a turbidity of less than or equal to 15 NTU. 17.The injection solution of claim 16, wherein the injection solution has aturbidity of less than or equal to 10 NTU.
 18. The injection solution ofclaim 1, wherein after the powder polymer is suspended in the watersoluble solvent for a period of at least 2 hours with a turbiditydecrease of at least 25%.
 19. The injection solution of claim 18,wherein after the powder polymer is suspended in the water solublesolvent for a period of at least 2 hours with a turbidity decrease of atleast 50%.
 20. The injection solution of claim 19, wherein after thepowder polymer is suspended in the water soluble solvent for a period ofat least 2 hours with a turbidity decrease of at least 75%.
 21. Theinjection solution of claim 1, wherein the polymer in the injectionsolution has an average particle size ranging from 0.01 to 10 μm. 22.The injection solution of claim 1, wherein the water soluable solventfurther comprises a glycol ether, an alcohol, a co-solvent, and mixturesthereof.
 23. The injection solution of claim 1, wherein the non-ionicsurfactant is selected from ethoxylated surfactants, nonylphenolethoxylates, alcohol ethoxylates, and mixtures thereof.
 24. Theinjection solution of claim 1, wherein the anionic surfactant isselected from internal olefin sulfonates, isomerized olefin sulfonates,alkyl aryl sulfonates, medium alcohol (C10 to C17) alkoxy sulfates,alcohol ether [alkoxy]carboxylates, alcohol ether [alkoxy]sulfates,alkyl sulfonate, a-olefin sulfonates (AOS), dihexyl sulfosuccinates,alkylpolyalkoxy sulfates, sulfonated amphoteric surfactants, andmixtures thereof.